1. Field of Invention
The present invention relates to a system for linking standard telephony communications using internet protocols.
2. Description of Background Information
Telephony communications systems connect various types of telephone communications equipment, including, e.g., digital and analog telephones, facsimile (sending and/or receiving) machines, and data and/or facsimile modems.
Such telephony communications systems may comprise a network of varying systems interconnected with various types of transmission links. Such interconnected systems may include, e.g., centrex systems, private branch exchange (PBX) systems, and key telephone systems.
Transmission links provide links across various physical distances, serving as, e.g., long-distance lines, local exchange carrier lines, foreign exchange lines, 800 WATS lines, and/or tie-lines. The physical connection may be made with the use of a cable, e.g., a twisted copper pair, fiber-optic cabling, two-wire open lines, coaxial cable, or it may be wireless, e.g., using cellular technologies, satellite transmission systems, terrestrial microwave links, radio links. One or more combinations of existing or future transmission technologies may be used, such as T1, CEPT PCM-30, SONET, ISDN, frame relay, and asynchronous transfer mode.
Telephony communications systems utilize switching networks to connect one telephony device (telephone, fax, modem, etc.) to another, in accordance with a telephone number (the telephony destination address) specified by one of the telephony devices to be connected. A telephone number over a public switch telephone network (PSTN) will typically comprise a three-digit area code (number plan area (NPA)), followed by a three-digit exchange code (sometimes referred to as NNX or NXX), and then a four digit code used to identify the specific telephone line of the destination telephony device.
An example of a telephony communications system is a public switched telephone network (PSTN). Access to the PSTN is provided using the telephony communications equipment, as well as other equipment such as hardwiring which is extended between the telephony communications equipment and a system with which it is interfaced. For instance, hardwiring may extend from the telephony communications equipment to a wall outlet, from the wall outlet to the building exterior, and from the building exterior to the telephony communications system. Alternatively, telephony communications equipment may access the telephony communications systems using a transmitter (e.g., cellular) or through other known means. In either case, a considerable amount of hardware is presently in place to provide communication between the telephony communications system (e.g., PSTN) and telephony communications equipment (e.g., telephone).
Conventionally, communications over telephony communications systems are performed based on a connection-oriented network model. In the connection-oriented network model, a pathway is formed between a source node and a destination node of the telephony communications system before communication begins, creating what is commonly referred to as a virtual circuit therebetween. The pathway is commonly established using a handshaking procedure in which the source node requests communication by informing the network of the destination node, the network then notifies the destination node of the request, whereupon the destination node accepts or refuses a request for communication. If the destination node accepts the request for communication, the source node, the destination node and all resources of the telephony communications system that are used to define the pathway therebetween are reserved for the communication.
Conventional PSTN-type telephony communications systems connect telephones as follows. The caller (source) requests a communication by dialing (informing) the PSTN of a telephone number (destination). After the telephone number has been dialed, the PSTN establishes a path, reserves whatever resources are necessary to maintain that path, contacts the destination by ringing its phone, and conducts the communication after the request is accepted. As such, the resources of the PSTN remain reserved from the time of inception of a communication to its completion.
Under the present regulatory scheme, communications over telephony communications systems are classified among three categories: intraLATA (“Local Access Transport Area”), interLATA and international. IntraLATA communication is performed when the source and destination nodes are both located in a single calling area; interLATA communication is performed when the source and destination nodes are located in different calling areas within a single country, and international communication is performed when the source and destination nodes are located in calling areas of different countries. Typically, the three categories rank as listed above in order of expense with intraLATA communications generally being provided at the lowest cost.
In view of the above, there is a need for a system that is capable of maximizing the communications of presently available resources, including resources not presently used by conventional telephony systems. There is also a need for a system that is capable of reducing costs associated with conventional telephony communications systems.
It is costly to reconfigure a given traditional telephony communications system, such as a centrex system, a PBX system, or a key telephone system. As just one example, the creation and testing of a new telephone circuit will be quite labor-intensive, requiring such actions as locating the switch, finding a suitable and available wiring connection to establish the telephone circuit, making many cross-connections between and/or splicing of cables to route the wiring to the desired end destination, and performing different testing and verification procedures to ensure that a proper connection is made. If at any critical point in the path of a circuit, the available lines reach their full capacity, new lines will need to be installed to accommodate new telephony circuits, or the circuit must be diverted in a less than optimal manner to utilize existing cable facilities.
Much effort has been spent recently to integrate computer technologies having much more flexibility with hard-wired/switched telephony systems, to thus combine the strengths of each of these areas. Computer telephony integration (CTI) standards have been developed for communications between computer and telephony platforms, including, e.g., computer supported telephony applications (CSTA) and switch-computer applications interface (SCAI), Versit, and the INTEL-proposed high-speed serial interface.
There is a need to further reduce limitations and configuration costs associated with hard-wired/switched telephony systems. There is also a need for systems facilitating the efficient utilization of computer systems and networks for telephony applications, for local intra-office, local extra-office, long distance and/or international voice, fax, and data communications.
3. Definition of Terms
The following term definitions are provided to assist in conveying an understanding of the various exemplary embodiments and features disclosed herein.
Connectionless-Style Network Layer Protocol:
A connectionless-style network layer protocol is defined in Chapters 5 and 7 of Radia Perlman's book entitled “Interconnections: Bridges and Routers,” Addison-Wesley (1992), pages 127–148 and 165–191. The content of the Chapters 5 and 7 of this book is hereby expressly incorporated by reference herein in its entirety. Examples of connectionless-style network layer protocols include, e.g., the CLNP and IP protocols.
Internet:
An internetwork comprising large computer networks interconnected over high-speed data links such as ISDN, T1, T2, FDDI, SONET, SMDS, OT1, etc. As described in Newton's Telecom Dictionary, the Internet accomodates a new computer that connects to the Internet by adopting the new connection as part of the Internet and beginning to route Internet traffic over the new connection and through the new computer. The Internet uses a connectionless-style network layer protocol.
Telephony Communications Equipment:
A device compatible with a telephony communications system. An example of such a device is one that initiates a connection by specifying, among other things, a telephony destination address, and completes a call connection when its telephony destination address has been specified by another device. Examples of telephony communications equipment include analog and digital telephones, cellular telephones, facsimile machines, and dial-out data and/or facsimile modems.